As an electronic device, for example, there is known a push-button telephone that has a button lighting structure which includes a plurality of button members arranged in a matrix and configured to light each button member, in other words, a button backlight structure.
As an example of the button lighting structure of this type, there has been disclosed a configuration that lights the button member by irradiating the inside of the button member with light from a light-emitting diode (LED) disposed directly below each button member (e.g., refer to Patent Literature 1).
For example, as shown in FIGS. 1 and 2, the button lighting structure includes: a plurality of button members 105 which are arranged in a matrix; case 103 which includes operation surface portion 111 having a plurality of openings 114 into which button members 105 are inserted; and LED 106 directly disposed below each button member 105. Further, as shown in FIG. 2, the button lighting structure includes: rubber contact 117 having support 117a for supporting the lower end of each button member 105; and circuit board 118 in which a switch element (not shown), pressed by each button member 105, and LED 106 are arranged.
Button member 105 includes top surface portion 105a pressed by a finger, and side wall portion 105b formed around top surface 105a. Button member 105 has an outer peripheral portion made of a color material and an inner peripheral portion made of a transparent resin material. The display portion, such as a numeral or a symbol, of top surface portion 105a is formed by extending a part of the inner peripheral portion to the outer peripheral portion.
In operation surface portion 111 of case 103, guide 112 is integrally formed along the peripheral edge of opening 114 to guide the movement of button member 105 pushed into opening 114. Transparent panel member 120 is disposed in operation surface portion 111 of case 103, and information display sheet 121 is held between operation surface portion 111 and panel member 120.
Rubber contact 117, made of a transparent resin material, is disposed on circuit board 118. Light from LED 106 is transmitted through support 117a of rubber contact 117 to be applied to the inner peripheral portion of button member 105, and reaches the display portion of top surface 105a to light it. A part of the light irregularly reflected by the inner peripheral portion of button member 105 also reaches the display portion to light it.